Caption: A back-up flight model for the Vanguard 1 satellite on display at the Kansas Cosmosphere in Hutchinson, Kansas, one of America's leading space and rocket museums. The actual Vanguard 1 was launched as America's second satellite on 17 March 1958. It was 16cm in diameter and weighed just 1.5kg, but it was the first satellite to derive its power from solar cells - seen here in housings around the circumference. Stub aerials or antennas for communications are also visible.